Unlock iPhone 3.1.3
Unlock iPhone 3.1.3 For 3G 3GS Using Ultrasn0w
Good news here because now you can unlock you iPhone 2G, 3G and 3GS 3.1.3 Firmware with old boot roms, and you can also can keep your baseband during upgrading to the latest firmware which is iPhone OS 3.1.3